Prepare ingredients: slice open avocado and remove seed. Finely chop onion and cilantro. Juice lime or lemon (I need slightly less than half a lime).

Scoop out avocado into a bowl with a spoon and roughly mash so it's still chunky.

Add in lime juice, cilantro, and onion. Also sprinkle in a little bit of salt and hot pepper/cayenne pepper.

Mix roughly. Taste to see if it's salty and spicy enough to suit your preference. Add a bit lime/lemon juice if you like the extra zing ;)

Last, fold in the diced tomatoes if using and add some black pepper if you want. Serve in a bowl, and garnish top with a bit of cilantro and couple pieces of tomato for a nice touch.

If not serving right away, wrap and refrigerate until ready to eat. Serve as a dip for chips, add to tacos and burritos, or sandwiches!